Apparatus for grinding and polishing strips of glass



Sept. 13, 1938. F. B. WALDRON ET AL 2,130,255

APPARATUS FOR GRINDING AND POLISHING STRIPS OF GLASS Filed Feb. 9, 1938 Patented Sept. 13, 1938 UNITED STATES PATENT OFFICE APPARATUS FOR GRINDING AND POLISH- ING STRIPS OF GLASS Brothers Limited,

Liverpool,

England, a limited-liability company In Great Britain March 9, 1937 Application February 9, 1938, Serial No. 189,536

4 Claims.

This invention relates to grinding and polishing apparatus operating simultaneously on both sides of a continuous strip of glass and has for its object improved means for driving the strip 5 through the apparatus.

In grinding and polishing apparatus of this type, such as is described and shown in the speciflcation of United States Patent No. 1,729,498, the grinding and polishing tools operating on one side of the strip are adjusted so that their operative surfaces lie in one plane, and thus form a support for the strip of glass. The strip is driven through the apparatus by means of pairs of rollers gripping the glass and located between the tools. In the arrangement according to the above-mentioned patent, each pair of rollers is adapted to float freely in'a direction perpendicular to the plane of the strip, so that the pair of rollers exerts no bending action on the strip. It

is, however, a mechanically simpler construction for one roller of each pair to be fixed and adjustable so that its surface in contact with the glass is accurately in the plane determined by the above-mentioned operative surfaces. There- 26 by, any bending of the strip is avoided.

Now it has been found that rollers having hard surfaces do not effectively or uniformly grip the glass, unless the pressure is so high that they are liable to break it, and this is more especially 30 so near the starting end of the apparatus, where the glass is rough. If,. however, rollers having soft surfaces are employed, such as soft rubber rollers, the yielding of the rollers makes it impracticable to maintain the rollers in such a position that bending of the strip is avoided.

According to the invention, all the rollers on that side of the glass on which the tools of the plurality are adjusted to lie in a plane, are also adjustably fixed with their upper surfaces in a plane, and are made of a material which yields so slightly under the gripping pressure employed, that the bending of the glass resulting from the yield is not harmful and the rollers on the other side of the glass which are pressed against it are made of a. relatively soft material adapted, under the pressure employed, to yield at least twice as much radially.

By means of this combination of rollers of a hard and a soft material respectively, harmful bending of the strip is avoided and efiective gripping is secured.

Preferably rubber is used for both the hard and soft material.

The permissible flattening of the hard roller depends on the thickness of the glass, and the of the lower tools 3, when their upper surfaces are distance of the roller from the tools. By way of example, with glass one-quarter inch thick when polished, and with the tool at a distance of one foot from the rollers, the flattening should be less than one-hundredth of an inch radially. 5

The flattening of the soft roller and its pressure on the glass should be sufficient to give an effective grip on the glass.

Applicants have found that, in their grinding and polishing apparatus, hard and soft rollers 10 which flatten respectively about seven and forty thousandths of an inch, give good results.

In the accompanying drawing:

Figure 1 is a diagrammatic part side view of a grinding apparatus; 15

Figure 2 is a side view of the bearing supports of a pair of rollers; and Figure 3 is a vertical section showing a pair of rollers gripping the glass.

The glass strip l is ground on both surfaces 20 simultaneously by the grinding tools 2 above the strip and the grinding tools 3, facing them, below the strip. The strip l is driven between the tools 2, 3 by pairs of rollers gripping the strip, of which the rollers 4 are above the strip 25 and the rollers 5 below it. The mounting of the grinding tools 2. 3 is shown diagrammatically since constructional details are shown in the above-mentioned Letters Patent. The shafts 6 of the tools turn in casings l which are adapted to slide vertically in frames 8 supported on girders 9. The shafts 6 are driven by gear wheels ill on sleeves slidingly keyed to the shafts. The lower tools 3 are adjusted in height, so that all their operative surfaces lie in a plane. To effect 35 this adjustment a bracket ll fixed to the casing 'l is supported by a screw-threaded rod l2 which passes through a bracket l3 on the frame 8 and engages a nut fixed to the bevel wheel 14. I

The upper tools 2 are yieldingly pressed on the 40 glass by means not shown. Referring to Figure 2, the shafts I5 and it of the rollers 4 and 5 turn in bearing blocks l1 and i8 respectively, which are adapted to slide between the frame uprights IS. The bearing block iii of 45 the lower roller is adjusted in height by the screw 20, and, by these screws 20 all the rollers below the glass are adjusted in height so that their upper surfaces lie in the plane of the operative surfaces O slightly flattened by the pressure of the glass on them. The upper rollers 4 are pressed on to the glass by means of screw-threaded rods 2| engaging the bearing blocks lI adapted to be turned by the gear wheels 2:. 55

Referring to Figure 3, the lower roller is composed of rubber 5 on the roller shaft I, which is of such hardness that it flattens only to a small extent indicated at 23 under the pressure between it and the glass. The upper roller is composed of much softer rubber I which flattens to the extent indicated at 24. The amount of flattening is exaggerated in the drawing for the sake of clearness.

Having described our invention, we declare that what we claim and desire to secure by Letters Patent is: p

1. Apparatus for grinding and polishing a glass strip comprising a plurality of disc tools adapted to operate on one side of the strip, a second plurality of tools adapted to operate on the other side of the strip, each tool of one plurality facing a tool of the other plurality, means for adjusting the tools of the first plurality so that their operative surfaces lie in a plane, a plurality of pairs of rollers adapted to grip the strip and drive it between the tools, means for adjusting into a plane the position of the rollers on that side of the strip on which the plurality of tools is adjusted into a plane, the material of the rollers on the said side of the strip being a yielding material but substantially harder than the material of the rollers on the other side of the strip.

2. Apparatus for grinding and polishing a glass strip comprising a plurality of disc tools adapted to operate on one side of the strip, a second plurality of tools adapted to operate on the other side of the strip, each tool of the plurality facing a tool of the other plurality, means for adjusting the tools of the first plurality so that their operative surfaces lie in a plane, a plurality of pairs of rollers adapted to grip the strip and drive it between the tools, means for adjusting into a plane the position of the rollers on that side of the strip on which the plurality of tools is adjusted into a plane, the material of the rollers on the said side of the strip being a yielding material but so much harder than the material of the rollers on the other side of the strip that, under the gripping pressure employed, it yields less than one-third as much radially.

3. Apparatus as in claim 1, in which the material of the rollers on one side of the strip is rubber adapted to yield under the pressure employed, and the material of the rollers on the other side of the strip is a softer rubber.

' 4. Apparatus as in claim 2, in which the material of the rollers on one side of the strip is rubber adapted to yield under the pressure employed, and the material of the rollers on the other side of the strip is a softer rubber.

FREDERIC BARNES WALDRON.

JAMES HARRIS GRIFFXN. 

